Light emitting devices, such as laser diodes or light emitting diodes that use group III-V or group II-VI compound semiconductors, are capable of emitting light of various colors, such as for example, red, green, blue, and ultraviolet light, owing to developments of device materials and thin-film growth technologies. Moreover, these light emitting devices are capable of emitting white light with high efficiency through use of a fluorescent substance or color combination, and have advantages including low power consumption, semi-permanent lifespan, fast response time, safety and environmental friendliness as compared to conventional light sources, such as fluorescent lamps, incandescent lamps and the like.
Accordingly, application sectors of light emitting devices are expanded up to transmitting modules of optical communication means, light emitting diode backlights that can replace Cold Cathode Fluorescence Lamps (CCFLs) constituting backlights of Liquid Crystal Display (LCD) apparatuses, white light emitting diode lighting apparatuses that can replace fluorescent lamps or incandescent lamps, automobile head lights, and traffic lights.
A light emitting device package is configured such that a first electrode and a second electrode are arranged on a package body, and a light emitting device is placed on a bottom surface of the package body and is electrically connected to the first electrode and the second electrode.
In the case of a light emitting device package in which a light emitting diode to emit ultraviolet light (UV) is mounted, if reflected ultraviolet light reaches a package body, an organic material contained in the package body is discolored or deteriorated, causing reduction in the reliability of the package. Thus, there exists a need to improve the reliability of the light emitting device package while maintaining excellent heat radiation properties.
FIG. 1 is a view illustrating a light emitting device package.
A package body 110 has a cavity, and a light emitting device 130 is placed on a bottom surface of the cavity. A radiator 180 may be disposed in a lower portion of the package body 110. The radiator 180 and the light emitting device 130 may be fixed to each other via a conductive adhesive layer 120.
However, the light emitting device package has problems as follows.
In FIG. 1, the radiator 180 may be formed of a high thermal-conductivity material. As the light emitting device 130 of the light emitting device package 100 may emit heat, the radiator 180 may undergo deterioration of planarity due to a difference in coefficients of thermal expansion between different constituent materials of the package body 110 and the radiator 180.
That is, in FIG. 1, the radiator 180 may have a roughened surface other than a flat surface due to volumetric expansion of the radiator 180, which causes tilting of the light emitting device 130, and consequently tilting of a light emission angle of the light emitting device package 100. In addition, the roughened radiator 180 provided at a lower surface of the light emitting device package 100 may cause the light emitting device package 100 to tilt when mounted onto a circuit board and the like.